The present invention relates to an electronic device, in which an electronic element is hermetically sealed, and a method for manufacturing thereof, and further a printed wiring board being suitable for use in such an electronic device.
Conventionally, an electronic element, such as a SAW (Surface Acoustic Wave) element, etc., is hermetically sealed within an electronic part case, for the purpose of protecting the property or characteristics of the SAW element from being damaged, and it is supplied in the form of an electronic device, such as a SAW filter device, etc. For sealing such an electronic element within the electronic part case, the element must be mounted and hermetically sealed within it, so that it has no contact with members constructing the case, while terminal portions thereof, being electrically connected to the element, must be led out to an outside of the case. For the electronic part case for use in such an arrangement, a ceramic case is well known. For example, with a electronic part, which comprises a built-in SAW element of surface-mount type therein, a chip of the SAW element is mounted within the ceramic case and it is treated with wire-bonding thereon, thereafter a cover is welded onto the case, thereby sealing between them. Also, the structure is disclosed, in which the SAW element is received or stored within a resin package while using the resin package in combination with a frame made from a resin plate and the cover on a wiring board made from a copper-clad laminate, for example, in Japanese Patent Laying-Open No. Hei 2-179018 (1990) and Japanese Patent Laying-Open No. Hei 10-16 647 (1998).
However, the form of those conventional electronic devices mentioned above is inappropriate or mass production of cheap and small-sized electronic devices in large number thereof, since the ceramic case itself is expensive and is not suitable material for small-size structures. Also, it is difficult to take or cut out large numbers of ceramic cases from a large-sized ceramic material. Also, the latter device mentioned above has a drawback that the characteristics of the built-in electronic element, such a the SAW filter element, etc., are deteriorated, since a frame made of resin is attached or adhered upon conductor patterns of the printed wiring board. Specifically, bonding power of the resin case on the conductor patterns on the printed wing board is weak and sealing property is low between them.
An object according to the present invention is, for overcoming such drawbacks in the conventional parts mentioned above, to provide an electronic device in which an electronic element is hermetically sealed, and a method for manufacturing thereof as well, and further a printed wiring board being suitable for use in such the electronic device, wherein a case is formed with attaching a frame member and a cover member made of resin upon the printed wiring board, but without using an expensive ceramic case, thereby being suitable for mass production of cheap and small-sized electronic devices, as well as being superior in hermetical sealing property of the case formed, so as to protect the built-in electronic device from being deteriorated in the characteristics thereof.
According to the present invention, for accomplishing such the object as mentioned above, there is provided an electronic device, comprising: a substrate of insulating resin having at least a pair of interior terminal portions for connection upon an upper surface thereof; an electronic element mounted on the terminal portions on the upper surface of said substrate, having at least a pair of electrode terminals thereof; a frame member of insulating resin, bonded on the upper surface of said substrate, and having a cavity formed for storing said electronic element therein; and a cover member of insulating material, for hermetically sealing over the cavity of said frame member, in which said electronic element is stored, wherein electrodes are formed at or in vicinity of positions of the terminals of said electronic element stored within said cavity, for electrically conducting said interior terminal portions for connection to an outside.
Further, according to the present invention, said electrodes for electrically conducting said interior terminal portions to the outside may be in the form of plated through-holes formed in said substrate, which is filled up with non-conductive resin therein, and in particular, being preferable to be non-penetrating through-holes, i.e., flat through-holes, each being covered with metal conductors on both side surfaces of the resin filled up within the plated through-hole. Also, according to the present invention, the electronic element stored within the cavity may be an optical element, and the cover member for sealing over the cavity may be made of transparent material.
Also, according to the present invention, there is provided an electronic device, comprising: a substrate of insulating resin having at least a pair of interior terminal portions for connection upon an upper surface thereof; an electronic element mounted on the terminal portions on the upper surface of said substrate, having at least a pair of electrode terminals thereof; a frame member of insulating resin, bonded on the upper surface of said substrate, and having a cavity formed for storing said electronic element therein; at least a pair of exterior terminal portions for connection, formed on an outer peripheral surface of said substrate, being electrically conducted to said interior terminals; and a cover member of insulating material, for hermetically sealing over the cavity of said frame member, in which said electronic element is stored, wherein roughened surfaces are formed on metal electrode portions, which are formed on the upper surface of said substrate for electrically conducting said interior terminal portions to said exterior terminal portions, where said frame member is bonded thereupon.
Further, according to the present invention, for accomplishing such the object as was mentioned above, there is also provided a printed wiring board for use in the electronic devices according to the above, comprising a plate made of insulating resin, and plural number of electrode portions for use of said terminals for interior connection, which are formed at or in vicinity of the electrode portions of plural number of the electronic devices to be mounted thereon, and in particular, they are preferable to be in the form of the flat through-holes.
Also, according to the present invention, there is further provided a printed wiring board for use in the electronic devices according to the above, comprising a plate made of insulating resin, and plural number of electrode portions for use of said terminals for interior connection, to be electrically conducted with plural number of electronic devices to be mounted, on at least one surface of said insulating resin plate, wherein surfaces of those electrode portions are roughened where said frame member is bonded thereon.
Moreover, according to the present invention, for accomplishing such the object as mentioned above, there is further provided a method for manufacturing an electronic device, comprising the following steps: (a) forming at least a pair of terminal portions for interior connection, on an upper surface of a substrate of insulating resin; (b) mounting an electronic element on the terminal portions for interior connection, on the upper surface of said substrate; (c) bonding a frame member of insulating resin on the upper surface of said substrate, so as to form a cavity, in which said electronic element is stored; and (d) bonding a cover member of insulating material on said frame member for hermetically sealing over said cavity thereof, in which said electronic element is stored, wherein in the step of said step (a), electrode portions are provided through forming flat through-holes at or in vicinity of positions of electrodes of the electronic element stored within said cavity, for electrically conducting said terminal portions for interior connection to an outside thereof.
And, also according to the present invention, there is further provided a method for manufacturing an electronic device, comprising the following steps: (a) forming at least a pair of terminal portions for interior connection, on an upper surface of a substrate of insulating resin; (b) mounting an electronic element on the terminal portions for interior connection, on the upper surface of said substrate; (c) bonding a frame member of insulating resin on the upper surface of said substrate, so as to form a cavity, in which said electronic element is stored; and (d) bonding a cover member of insulating material on said frame member for hermetically sealing over the cavity thereof, in which said electronic element is stored, wherein in the step of said step (a), roughened surfaces are formed on metal electrodes, which are provided for electrically conducting said terminal portions for interior connection to an outside thereof, where said frame member is bonded thereon.